Henry a



(No Model.)

H..A. CHASE. MAGNETO TELEPHONE- No. 5161642. Patented Mar. 20, 1894.

in V6 nfor gym. 51km UNITED STATES ATENT rrron.

HENRY A. CHASE, OF BOSTON, MASSACHUSETTS, ASSI GNOR TO ALBERT WATTS, OFSAME PLACE.

MAGNETO-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 516,642, dated March20, 1894.

Application filed August 12, 1893.

To all whom it may concern.-

Be it known that I, HENRY A. CHASE, residing in Boston, in the county ofSuffolk and State of Massachusetts, have invented an Improvement inTelephones, of which the following description, in connection with theaccompanying drawings, is a specification, like letters on the drawingsrepresenting like parts. This invention relates to an improvement inthat class of telephones known as the handphone, and has for its objectto provide an instrument, the parts of which are capable of expansionand contraction without disturbing the relative position or equilibriumof the usual diaphragmand its pole piece, where by the distance betweenthe said diaphragm and its pole piece is maintained substantiallyconstant and is not disturbed by the movement of the case or of thepermanent magnet.

In accordance with this invention, the exciting magnet, usually in theform of bar mag nets, has rigidly secured to it a soft iron pole pieceafter the manner now commonly practiced in the ordinary Bell handphone.The exciting magnet and its pole piece are secured at or near the frontend of the inclosing case or shell, which is usually made of hardrubber, they being secured as herein shown by means of a bridgepreferably in the form of a disk screwed or otherwise fastened to theinterior of the case.

In order to permit of the expansion and contraction of the hard rubbercase and the exciting magnet without disturbing the position of the softiron pole piece with relation to its diaphragm, the exciting magnet isunattached at its rear end from the hard rubber case and may be providedwith an extension preferably in the form of a cylindrical bar or rod,which extends into a suitable hole or socket in the back of the case,the said hole or socket in this instance forming a bearing for the rearend of the exciting magnet. The rate of expansion of the hard rubbercase and of the exciting magnet being different, produces an unequalmovement of the case and exciting magnet when subjected to changes intemperature, such as experienced in actual service, the movement of thecase or shell being greatly in excess of the bar magnet. By leaving therear end of the exciting magnet unattached from the case or Serial No.482,983. (No model.)

shell, the latter is free ,to expand and contract without producingmovement or without affecting the exciting magnet, which is also free toexpand and contract independent of the case. By this construction, eachpart of the handphone is capable of responding to changes in temperaturewithout effecting the expansion or contraction of the other part.

The drawing represents in longitudinal section a hand telephoneembodying my invention.

The telephone case A, the cap A and the diaphragm A are and may be ofany usual or well-known construction. The case Acontains within it anexciting magnet, which may and preferably will be a compound bar magnetB composed, as herein shown, of four parts firmly secured together .atboth their front and rear ends by the bolts 2) b. The bolt b passesthrough ahole or opening in the rear end of the usual soft iron polepiece 6 and serves to firmly clamp or secure the said pole piece to thebar magnet B in the manner now commonly practiced in the ordinary Bellhandphone. The bolt 1) also firmly secures to the compound bar magnetthe back pole piece 12 which may be provided with an extension b hereinrepresented as cylindrical in shape, and which extension projects into ahole or socket b in the back piece b of the inclosing case A, thefinishing disk t being also provided, as herein-shown, with a hole orsocket b -in line with the socket b". The front pole piece I) is shownas extended through a support 0 preferably made as a disk, which may besecured to the inside of the case or shell A by suitable screws 0, thesaid disk being preferably provided with a threaded opening throughwhich the pole piece is ex-.

provided at its end with a slot 0 for the reception of a screw-driver orother suitable tool by which the pole piece may be adjusted withrelation to the diaphragm A the cap A and diaphragm being first removed.

It will be noticed that the front pole piece in temperature independentof the case.

b and the rear pole piece b are rigidly secured to the compound barmagnet B, which construction is the same as that found in the Bellhandphone as now commonly constructed. It will further be noticed thatthe compound bar magnet is supported at its front end by the pole pieceb and the disk 0, while its rear end is supported by the extension b ofthe back pole piece 12 It will further be noticed that the back polepiece 12 is entirely disconnected or unattached from the case andconsequently the latter is free to expand and contract independent ofthe bar magnet B, so that the case A may respond to changes intemperature without affecting or influencing or being influenced by thepermanent magnet B, which by reason of its disconnection at one end, isfree to respond to the changgs n this manner, the front pole piece 12when once adjusted with relation to the diaphragm A will remainsubstantially constant and be nninfluenced by the ordinary changes oftemperature, and if by reason of very severe or wide differences intemperature, the adj ustment of the pole piece 6 with relation to thediaphragm A. should be disturbed, it can be readily corrected byremoving the cap A and the diaphragm A and turn the pole piece 17 so asto change its position with relation to the diaphragm A I claim- 1. In atelephone, the combination with an inclosing case provided at its rearend with a hole or socket, of a permanent magnet provided with a frontpole piece rigidly attached to it and having a back pole piece providedwith an extension projectinginto said socket but disconnected from thesaid case, and a support for the front pole piece secured to the saidshell or case, substantially as described.

2. In a telephone, the combination with an inclosing case, of apermanent magnet having one end free from or unattached to the inclosing case and provided at its opposite end with a pole piece rigidlyattached to the permanent magnet, and a support for the said pole pieceattached to the inclosing case, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

HENRY A. CHASE.

\Vitnesses:

J AS H. CHURCHILL, J. MURPHY.

